I'm a delivery driver for Jason's Deli. I drive 90% city. 10% highway. I start my car close to 15 times a day. I get around 260 miles driven on 16 Gallons of gas filled up and there is nothing wrong with this number. I am constantly diving in and out of traffic in very busy Nashville traffic areas. OP I don't think you ever posted how you drove city/highway. That is really important because my car does DRASTICALLY better when I'm flip flopped 90% Highway 10% city I get nearly 460 miles on 16 gallons filled up

 

and they didn't believe my numbers....

 

Yah, I'm pretty sure that 115 mph top speed is for a GXE with rev limiter, due mainly to the reduced speed rating of the OEM tires.